NECO SSCE - Physics - 2000

A radioactive substance has a half-life of 3 minutes. After 9 minutes, the count rate was observed to be 200. What was the count rate at zero time?

The image obtained on the screen of a pin-hole camera becomes less sharply defined when the

When a lever is in equilibrium, under the action of two or more forces, the algebraic sum of the moments of the forces about the point of support is

The force exerted on a charged body in an electric field depends on

I. the charge on the body
II. the electric field intensity
III. the square of the mass of the body

The specific heat of a substance in the solid state is C₁; its specific beat in the liquid state is C₂ and its latent heat of fusion is L. If a mass M of the substance is changed from the solid state at temperature T, to the liquid state, also at temperature T, the amount of heat required will be

When electrical power is transmitted over long distances, the voltage is stepped up so that

If a positively charged glass-rod is used to charge an electroscope X by contact and an electroscope Y by induction, then

The image is a plane mirror is

An electric iron rated 250 V has a coil of resistance 125Ω. What is the cost of using it for I hour at 10k per kWh?

The smallest unit on the sleeve of a micrometer screw gauge is 0.5mm. There are fifty divisions on the thimble of the screw gauge.
What is the smallest length that can be measured with this instrument?

A piece of stone weights 180 N in air and 150 N in a beaker containing 160 N of methylated spirit. What is the up thrust exerted on the stone?

What is the coefficient of static friction between a load of mass 2kg and a horizontal surface, if the limiting frictional force is 10N? (g = 10 ms^-2)

The heat from a fire in a closed room reaches someone far away in the room, mainly by

A wave travels a distance of 20 cm in 3s. The distance between successive crests of the wave is 4cm. What is the frequency of the wave?

Calculate the peak voltage of a mains supply of r.ms. value 220V.

The clinical thermometer differs from other mercury-in-glass thermometers because it has

I. a constriction
II. a wide range
III. a short range
IV. a narrow bore.

Which of the above are correct?

In a simple pendulum experiment, a boy observed that the times for 30 oscillations are 70.0s, 72.0s and 67.0s respectively. Calculate the mean period of oscillation of the pendulum.

A gas occupies a certain volume at 27°C. At what temperature will its volume be twice times the original volume assuming that its pressure remains constant?

A man at the back of a crowd watches a parade by holding a plane mirror just above his head. The parade passes 6 metres behinde his head and the mirror is 0.25m in front of the man. How far does the image in the mirror appear to be from the man?

Which of the following is/are TRUE of nuclear fission?

I. A heavy nucleus is split into two nuclei of comparable masses
II. Two light nuclei are joined together to form a heavier nucleus
III. The total mass of the products is less than that of the reactants

An electric bell operated within an evacuated bell jar enables us to infer correctly that

Which of the following is used in a nuclear reactor to slow down fast moving neutrons?

The length of a side of a metallic cube at 20° C is 5.0cm. Given that the linear expansively of the metal is 4.0 × 10^-5K^-1, find the volume of the cube at 120° C

The half-life of a radioactive substance is 2 seconds. Calculate the decay constant.

A block of a substance X will sink in a liquid V but float liquid Z. Which of the following statements is NOT correct about the densities of the three substances?

A solid weights 5.0 N in air, 4.2 N in water and 4.4 N in liquid Y. Calculate the relative density of liquid Y.

When a metal is heated to a high temperature, electrons are emitted from its surface. The process is known as

The helium isotope \(^3_2He\)

A boy moving with a velocity of 3 ms^-1 is brought to rest by a constant force after travelling 15m. Calculate the retardation.

The image formed by a converging lens of focal length is of a distance of 2f from the lens. Calculate the lateral magnification produced

If the first position of resonance in a resonance tube is 18.0cm from the open end, the distance from the open end to the next position of resonance will be

A boy ran a distance of 200m in 24s. His average speed was 8.3ms^-1. Which of the following is correct about the units in which the statements above are expressed?

An astronomical telescope which is being used to view a very distant object is said to be in normal adjustment if

Two forces forming a couple are separated by a distance of 25cm. If one of the forces equals 40N, what is the moment of the couple?

400g of cold water is added to 200g of water at 70°C. If they are properly mixed and the temperature of the mixture is 300°C. calculate the initial temperature of the cold water. (Neglect the heat absorbed by the container)

To keep a lorry moving at a constant speed v, requires power p, from the engine. The force provided by the engine is

The unit of inductance is

I. A scalar quantity has only magnitude
II. A scalar quantity has both magnitude and direction
III. A vector quantity has both magnitude and direction
IV. A vector quantity has only magnitude.

Which of the above statement is/are correct?

A man standing 510m away from a wall sounds a whistle. The echo from the wall reaches him 3s later. Calculate the velocity of sound in air.

Which of the following is/areNOT affected by a magnetic field?

I. Alpha particle
II. Cathode rays
III. Neutrons

An element of nuclear number A and proton number Z emits an alpha particle from its nucleus. The nucleon number and the proton number of the new element formed are respectively

Which of the following pairs of light rays shows the widest separation in the spectrum of white light?

Two 2.0Ω resistors can be combined circuit to give an overall resistance of

A particle of charge q and mass m moving with a velocity v enters a uniform magnetic field B in the direction of the field. The force on the particle is

Which of the following is NOT part of an a.c generator?

Which of the following statements about evaporation and boiling is FALSE?